Graphene Photodetectors Toward Practical Technologies for Biosensing: Mechanisms, Architectures, Applications, and Integration Challenges

Graphene, with its 2D structure, zero bandgap, high carrier mobility, and broadband absorption, is an ideal platform for next-generation photodetectors with substantial promise for biosensing applications. This review summarizes recent progress in graphene photodetectors along the following two lines: device physics and applications. At the device level, the following three types are discussed: heterojunction, photogating, and photothermoelectric/plasmonic. Performance enhancements via band engineering, interface control, and nanostructure design are revealed. For example, a SiO2/CuO buffer layer in heterojunction detectors achieves an on/off ratio of 1.1 × 102, greatly improving responsivity. At the application level, breakthroughs and challenges in extreme environment monitoring, flexible wearables, large-scale integration, multifunctional intelligent sensing, and full-band detection are explored. These advances show broad prospects in biomedical sensing, wearable health monitoring, intelligent imaging, high-speed optical communication, and defense. This review constructs a knowledge graph covering physical mechanisms, material processes, and system applications. It analyzes core contradictions in performance trade-offs, process compatibility, and system integration and outlines the following future directions: exploring new physical mechanisms, CMOS-compatible heterogeneous integration, and intelligent sensing memory computation integration. The goal is to provide theoretical and technical guidance for transitioning graphene photodetectors from the lab to practical applications, including biomedical diagnostics and wearable healthcare systems.